Abrupt Ice Age Shifts in Southern Westerlies and Antarctic Climate Forced from the North

Buizert, Christo; Sigl, Michael; Severi, Mirko; Markle, Bradley R.; Wettstein, Justin J.; McConnell, Joseph R.; Pedro, Joel B.; Sodemann, Harald; Goto-Azuma, Kumiko; Kawamura, Kenji; Fujita, Shuji; Motoyama, Hideaki; Hirabayashi, Motohiro; Uemura, Ryu; Stenni, Barbara; Parrenin, Frédéric; He, Feng; Fudge, T. J.; Steig, Eric J. (2018). Abrupt Ice Age Shifts in Southern Westerlies and Antarctic Climate Forced from the North. Nature, 563(7733), pp. 681-685. Springer Nature 10.1038/s41586-018-0727-5

	Text Buizert_2018_Nature.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (7MB) | Request a copy
Preview	Text Buizert_2018_Nature_accepted.pdf - Accepted Version Available under License Publisher holds Copyright. Download (1MB) | Preview

The Southern Hemisphere (SH) mid-latitude westerly winds play a central role in the global climate system via Southern Ocean upwelling, carbon exchange with the deep ocean, Agulhas Leakage, and Antarctic ice sheet stability. Meridional shifts in the SH westerlies have been hypothesized in response to abrupt North Atlantic Dansgaard-Oeschger (DO) climatic events of the last ice age, in parallel with the well-documented shifts of the intertropical convergence zone. Shifting moisture pathways to West Antarctica are consistent with this view, but may represent a Pacific teleconnection pattern. The full SH atmospheric-circulation response to the DO cycle, as well as its impact on Antarctic temperature, have so far remained unclear. Here we use five volcanically-synchronized ice cores to show that the Antarctic temperature response to the DO cycle can be understood as the superposition of two modes: a spatially homogeneous oceanic “bipolar seesaw” mode that lags Northern Hemisphere (NH) climate by about 200 years, and a spatially heterogeneous atmospheric mode that is synchronous with NH abrupt events. Temperature anomalies of the atmospheric mode are similar to those associated with present-day Southern Annular Mode (SAM) variability, rather than the Pacific South America (PSA) pattern. Moreover, deuterium excess records suggest a zonally coherent migration of the SH westerlies over all ocean basins in phase with NH climate. Our work provides a simple conceptual framework for understanding the circum-Antarctic temperature response to abrupt NH climate change. We provide observational evidence for abrupt shifts in the SH westerlies, with ramifications for global ocean circulation and atmospheric CO₂. These coupled changes highlight the necessity of a global, rather than a purely North Atlantic, perspective on the DO cycle.

Interest & Impact

Downloads

137 since deposited on 21 Apr 2020
36 in the past 12 months

Citations

5 Citations in Web of Science ®
6 Citations in Scopus

Search

in Google Scholar™

Services

Actions (login required)

Edit item

Actions (login required)

Edit item